TY - JOUR
T1 - Mechanisms of Action of Growth Hormone-Releasing Peptide-2 in Bovine Pituitary Cells
AU - Roh, S. G.
AU - He, M. L.
AU - Matsunaga, N.
AU - Hidaka, S.
AU - Hidari, H.
PY - 1997/10
Y1 - 1997/10
N2 - We conducted this study to investigate the mechanisms of action of growth hormone-releasing peptide-2 (D-Ala-D-βNal-Ala-Trp-D-Phe-Lys-NH2; GHRP-2) in bovine anterior pituitary primary cell culture. Doses of GHRP-2 from 10-13 to 10-7 M increased (P < .05) GH secretion. The GHRP-2 (10-7 M) and GH-releasing factor (GRF; 10-7 M) administered together had an additive effect on the release of GH (P < .05). Somatostatin (1 μM) decreased GH secretion in response to GHRP-2 and(or) GRF (P < .05). Secretion of GH in response to GHRP-2 was blocked (P < .01) by a GRF receptor antagonist (.1 μM). Nifedipine (10 μM), a voltage-dependent Ca 2+ channel blocker, inhibited (P < .01) GHRP-2-stimulated GH release. The GH release in response to GHRP-2 and 4β-phorbol-12-myristate-13-acetate (10-7 M), a protein kinase C activator, was additive (P < .01). Forskolin (30 μM), a cAMP elevating agent, further stimulated (P < .01) the GH release in response to GHRP-2. Bovine GH concentrations in culture media were assayed by indirect competitive enzymeimmunoassay. These results showed that GHRP-2 1) stimulates GH secretion from bovine pituitary cells, 2) may partially act via GRF receptor, 3) has GH secretion activity caused by Ca2+ influx via Ca2+ channels, and 4) may increase GH secretion via protein kinase C and cAMP pathways.
AB - We conducted this study to investigate the mechanisms of action of growth hormone-releasing peptide-2 (D-Ala-D-βNal-Ala-Trp-D-Phe-Lys-NH2; GHRP-2) in bovine anterior pituitary primary cell culture. Doses of GHRP-2 from 10-13 to 10-7 M increased (P < .05) GH secretion. The GHRP-2 (10-7 M) and GH-releasing factor (GRF; 10-7 M) administered together had an additive effect on the release of GH (P < .05). Somatostatin (1 μM) decreased GH secretion in response to GHRP-2 and(or) GRF (P < .05). Secretion of GH in response to GHRP-2 was blocked (P < .01) by a GRF receptor antagonist (.1 μM). Nifedipine (10 μM), a voltage-dependent Ca 2+ channel blocker, inhibited (P < .01) GHRP-2-stimulated GH release. The GH release in response to GHRP-2 and 4β-phorbol-12-myristate-13-acetate (10-7 M), a protein kinase C activator, was additive (P < .01). Forskolin (30 μM), a cAMP elevating agent, further stimulated (P < .01) the GH release in response to GHRP-2. Bovine GH concentrations in culture media were assayed by indirect competitive enzymeimmunoassay. These results showed that GHRP-2 1) stimulates GH secretion from bovine pituitary cells, 2) may partially act via GRF receptor, 3) has GH secretion activity caused by Ca2+ influx via Ca2+ channels, and 4) may increase GH secretion via protein kinase C and cAMP pathways.
KW - Cattle
KW - Growth Hormone
KW - Hypothalamic Releasing Hormones
KW - Pituitary Gland
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U2 - 10.2527/1997.75102744x
DO - 10.2527/1997.75102744x
M3 - Article
C2 - 9331879
AN - SCOPUS:0031253840
SN - 0021-8812
VL - 75
SP - 2744
EP - 2748
JO - Journal of Animal Science
JF - Journal of Animal Science
IS - 10
ER -